1. Field of the Invention
The present invention relates to an equipment interface for obtaining data communicated between a tool and its host computer system and distributing the data. More particularly, the invention relates to an equipment interface for obtaining a live stream of data communicated between a semiconductor manufacturing tool and its host computer system and distributing the data to remote application programs requesting the data.
2. Description of the Related Art
Technological advances have produced increasingly complex manufacturing systems, and accordingly, increasingly complex manufacturing management systems are necessary. Information must be gathered to determine output requirements, to procure raw materials, to allocate manufacturing resources, to schedule work in various manufacturing processes, to track work in progress, to troubleshoot and correct manufacturing problems, to measure actual manufacturing performance, to compare actual performance to performance goals, and to control quality of units produced. The sources of information used to make these management decisions vary widely, from product sales data to shop personnel to the actual manufacturing tools themselves. Many manufacturing facilities manage this vast information by combining computerized management systems with paper-based management systems.
A particular management challenge in the manufacturing environment is communicating time-critical performance information to management and shop personnel so that performance problems may be corrected as soon as possible. In a manufacturing environment involving many processing steps, errors detected near the time they are made may be correctable before the product moves on to other processing steps. Significant cost savings are possible if a problem in the manufacturing shop renders a product unusable and additional processing steps on the unusable product are avoided.
Most manufacturing facilities use a variety of enterprise data management systems (EDMS) that manage enterprise-wide information. EDMS may include enterprise resource planning (ERP) subsystems that monitor, schedule and validate production inputs such as materials, equipment, personnel, work instructions and facility conditions. However, EDMS typically include only enterprise-level information and do not integrate real-time status information collected from tools in the manufacturing shop that would be useful to management and shop personnel. The term real-time is used herein to describe any electronic operation fast enough to keep up with its real-world counterpart, in this case, transmitting live tool status information immediately when an event occurs.
Another limitation of EDMS is that most EDMS communicate to personnel via only a pull model, where personnel must specifically request information from a particular source. For example, to obtain work in progress (WIP) information, personnel must ordinarily request a WIP report from the EDMS. In contrast, in a system using a push model, data is automatically delivered into computer systems at prescribed intervals or based upon the occurrence of particular events. These particular events may include automatically generated requests, or automated pulls, of information, so that personnel automatically receive certain information without requesting it. The term push is used herein to describe systems where information is automatically provided to personnel.
Capturing comprehensive manufacturing status information in real-time and timely communicating that information to management and shop personnel is highly desirable. Communicating timely information is especially difficult in large manufacturing facilities where management personnel are located at a distance from the manufacturing shop or in facilities where shop personnel work in a secure area separated from other personnel.
Problems with capturing and communicating information are exacerbated in a semiconductor manufacturing environment. Manufacturing of integrated circuits is perhaps the most complex manufacturing process in existence today. Factors contributing to this complexity include constant device miniaturization, process intricacy, product diversity, and changing technologies. Management of the semiconductor manufacturing process is accordingly complex and may involve thousands of steps performed on a silicon wafer to produce a fully packaged and integrated electronic component. An error in one process performed can render a particular lot of wafers unusable, so that timely detection and correction of problems in the manufacturing process can save significant resources.
Semiconductor manufacturing processes must occur in an environment free of contamination, so that semiconductor manufacturing facilities include a clean room in which the air is highly filtered to keep out impurities. Clean room personnel perform an elaborate procedure to clothe themselves in xe2x80x9cbunny suitsxe2x80x9d which are required to keep them from contaminating the air. These elaborate procedures to enter the clean room environment are a barrier to direct and immediate communication between management and clean room personnel. Another barrier is the limited ability to use computers to communicate because devices inside the clean room must not contaminate the clean environment, and support of computers within the clean room environment is difficult.
Most communication between management and clean room personnel occurs during regular personnel meetings outside the clean room. However, regular meetings do not address the problems of communicating time-critical information about problems that arise between meetings. Managers can communicate information to clean room personnel during shift changes; however the time for shift changes must be very limited to avoid stalling production in the clean room. Once personnel have entered the clean room, communication with them may be accomplished in a number of ways. One method requires that the manager suit up and enter the clean room, where the ability to communicate is hindered and the communication is disruptive to clean room activities. Another method is that the information be announced over a loudspeaker, a poor way of communicating detailed technical information. Similarly, other known methods, such as using phones, pagers, and e-mail, are also limited. In addition, none of these methods provides immediate performance information to manufacturing shop personnel that can serve as a motivator.
In some semiconductor manufacturing facilities, specially-designed terminals reside in the clean room so that clean room personnel can request WIP information from the EDMS. However, typically the EDMS does not provide reports of time-critical information such as real-time tool status that are useful to clean room personnel. While real-time information may be available from the EDMS, access may be restricted to authorized personnel. Furthermore, the real-time information may available but require significant effort and resources to use it for managing the manufacturing environment.
Furthermore, most EDMS operate using a pull model so that time-critical information may not be brought to the attention of personnel if reports are not requested. Finally, the information presented on the terminal may not be not easily visible by clean room personnel while they are performing their work because the primary use for the terminal is to present other clean room status information.
A system is desirable that uses a push model, where data is automatically delivered to management and clean room personnel at prescribed intervals or based upon the occurrence of particular events. Furthermore, a system is desirable that automatically and continually updates presentations of data when events occur in the manufacturing shop. Providing time-critical information to personnel without the need for personnel initiating a report request would enable manufacturing shop personnel to operate the shop more efficiently and managers to address performance problems more quickly to effectively manage the manufacturing environment.
It is also known that a tool in an automated environment is controlled by a host computer system running a software intermediary, called an equipment interface. A tool and its host computer system are typically connected via a serial cable running from the tool to the host. The equipment interface controls the operation of the tool and the flow of information from the tool to its host computer system is critical to the entire manufacturing process. If one tool is unavailable, an entire production lot may be rendered unusable.
An equipment interface and a tool communicate with each other via a communication language/standard such as that known as SECS/GEM (SEMI Equipment Communications Standards/Generic Equipment Model). Tools have a common language, though the specifics of the communication may differ. The equipment interface typically receives SECS message streams from the tool regarding status and activities of the tool and sends SECS messages to instruct the tool to perform certain activities. The equipment interface typically records the tool/equipment interface communications in a communication log file, which is stored on the host computer system.
SECS-I is the general message transfer layer of the SECS standards. SECS-I defines the transfer of binary messages between a host computer system and one tool. Because this communication is from one point (the host computer system) to another (the tool), the connection is often called point-to-point. Communication under SECS-I is through a serial connection, such as an RS-232 link. In manufacturing management system 110, a tool interface 134 includes the hardware for the serial connection between a tool 132 and its host computer system.
A SECS-I driver is a library of software that allows the host or equipment to communicate using the SECS-I standard. Typically, the library includes modules for error handling, requesting retransmission of blocks, sorting blocks by message, pasting blocks together in the right order to create messages, and matching responses to messages. Through an elaborate and robust protocol, SECS-I makes message transfer reliable.
SECS-II is the layer that is mostly specific to the semiconductor industry and is designed to use SECS-I. SECS-II defines powerful data structures, a dictionary of data items that use those structures, and standard messages used in conversations with semiconductor equipment.
The term SECS message is used herein to describe both SECS-I and SECS-II messages.
Information that a tool can provide via a SECS message is limited. In general, the data contained in a SECS message includes events related to the tool""s processing of material, such as a lot of wafers, and any errors encountered during the processing of the material. For example, a tool may be able to detect when it began processing material, when it completed that processing, and when errors or faults were detected. The tool itself may be unable to determine whether it was processing production, engineering, or qualification wafers.
A SECS message contains several pieces of information, including a general identifier that describes the type of message that follows (e.g., an alarm, a processing event, tool set-up, recipe download, etc.) and the data appropriate for the message type. SECS messages contain tool status information that the tool can provide, such as the tool state, tool events, tool set-up, and tool alarms. Some tools are configured to provide automatically additional information in these messages, such as recipe name, lot ID, and wafer number, which provides information about the context in which an event took place. This additional information is called a report. Other tools are not configured to provide reports automatically.
For example, a SECS message may contain a lot start event or a lot complete event. A report for these events may indicate the lot ID of the lot being processed, which enables the equipment interface to determine that the lot processed is a production lot. Productive time for the tool may then be calculated from the times of the lot start event and the lot complete event.
Message types are pre-defined by the SECS standard, but the events and reports (additional information attached to an event, such as material ID, recipe name, wafer number, etc.) vary by manufacturer and tool type. As mentioned earlier, some tools automatically provide pre-defined reports.
Manufacturing shops are configured to provide tool status information in real-time directly from a tool to its host computer system. The equipment interface uses the tool status information to control the tool, and therefore the connection between the equipment interface and the tool is critical. However, equipment interfaces typically do not provide real-time information to other application programs involved in managing the manufacturing process.
One method by which SECS messages communicated via a serial connection may gathered from a tool is to place an intermediary computer system between the tool and its host computer system. The single point-to-point connection between the tool and its host computer system is replaced with two point-to-point connections, one between tool and the intermediary computer system, and the other between the intermediary computer system and the host computer system. Each message communicated between the tool and the host computer system is received and copied by the intermediary computer system, and the message is passed along to its intended destination.
However, this method is very risky due to the critical nature of the equipment interface in controlling the tool. An intermediary computer system delays each message and introduces a potential failure point between the tool and its host computer system.
Another disadvantage of using an intermediary computer system is that two computer systems, the host computer system and the intermediary computer system, are required for each tool in the manufacturing shop. This solution is very expensive to implement in a manufacturing environment with a large number of tools. The expense of implementing such a system includes hardware costs, facility costs for housing the hardware, and management costs for managing the hardware and balancing the increased burdens on the facility.
Another method for obtaining tool status information directly from the tool is to use host-tool communication log files. Host-tool communication log files are created and updated by the equipment interface to include all communications between the tool and its host computer system. Using the host-tool communication log files enables application programs to obtain the information without the need for additional hardware or software to intercept the data. Advantages of this method include reducing the need for computers, obviating the need for additional cabling, providing a centralized single database, and allowing simplified system management (in a single proximal location).
However, the communication log file is also critical to the operation of a manufacturing tool. The equipment interface controls the operation of the tool in the manufacturing shop based upon the communications it receives and logs. To eliminate collisions and competition for accessing the communication log file, programs other than the equipment interface typically are prevented from accessing the communication log file until the file reaches a particular size, such as one megabyte. Then the equipment interface switches to another communication log file and the previous communication log file""s data may be accessed. Depending on the number and size of messages communicated between a particular tool and its host computer system, the delay in accessing the communication log file may be unacceptably long.
It is desirable to obtain tool status information continually (in near real-time considering processing delays) and to provide the tool status information to other remote application programs so that tool performance problems may be quickly detected and corrected.
The present invention relates to an equipment interface which obtains data communicated between a tool, such as a semiconductor manufacturing tool, and its host computer system in real-time via a point-to-point connection. The equipment interface provides the data to other remote application programs in near real-time without the need for hardware to be added to the tool or to the host computer system.
In one aspect of the invention, a method for distributing data communicated via a point-to-point connection between a tool and a host computer system is disclosed. The method includes providing an equipment interface on the host computer system, obtaining the data to be distributed from the point-to-point connection with the equipment interface, and providing the data with the equipment interface to at least one data requester. A data requester includes a remote application program requesting the equipment interface to provide the data communicated via the point-to-point connection.
In another aspect of the invention, an equipment interface for distributing data communicated via a point-to-point connection between a tool and a host computer system is disclosed. The equipment interface resides on the host computer system. The equipment interface includes a connection handler for providing a connection between the equipment interface and a data requester and a message handler for distributing the data to the data requester via the connection provided by the connection handler.
In another aspect of the invention, a tools data handler for obtaining tool status information and for processing tool status information is disclosed. The tools data handler includes an equipment interface for obtaining the tool status information. The tools data handler optionally includes a parser for processing tool status information and a database server application for processing tool status information.
In another aspect of the invention, a computer system for obtaining tool status information is disclosed. The computer system is connected to a tool via a point-to-point connection and serves as a host to the tool. The computer system includes a processor and memory. The memory is configured with a module for obtaining the data to be distributed from the point-to-point connection and a module for providing the data to a data requester.
In another aspect of the invention, a signal embodied in a carrier wave is disclosed. The signal includes instructions for obtaining data to be distributed from a point-to-point connection between a tool and a host computer system for the tool and for providing the data to a data requester.